1. Area of the Art
The present invention is in the area of medical devices and procedures and is more specifically directed towards a medical device and procedure for limiting nerve and inflammatory damage during pelvic surgeries, particularly during radical prostatectomy.
2. Background
Many surgical procedures have at least some side effects. Not unexpectedly, the more extensive the surgery, the more extensive the likely side effects. However, even relatively limited surgeries may have temporary or permanent side effects. In particular pelvic surgeries such as those dealing with the urogenital system may have more or less pronounced side effects. For example, the relatively common radical prostatectomy may have a variety of side effects. Following prostate surgery the patient often experiences temporary or even prolonged-permanent difficulties with urinary incontinence. In addition, prostate surgery frequently results in minor to profound sexual dysfunction. This is, perhaps, not surprising because male sexual functioning relies on an interaction between the nervous system, the endocrine system and the circulatory system. The pelvic region is a plexus of many nerves, and nerve fibers may be severed or damaged during prostate surgery. Furthermore, removal of the prostate traumatizes neuromuscular tissues causing inflammation and subsequent dysfunction. As a result, increasingly sophisticated and relatively non-invasive prostate surgeries have been developed to “spare nerves.” Many of these procedures involve microscopic robotic surgeries. With these techniques one can demonstrate that few if any nerves are actually severed. Nevertheless, these surgeries continue to result in significant urinary incontinency and impotence in patients due to stretching of the nerves (traction injury) as well as inflammatory damage resulting in dysfunction of surrounding structures. This problem is not unique to prostatectomy—other pelvic surgeries such as extravesical ureteral reimplantation, radical cystectomy, colorectal surgery including abdominal perineal resection, low anterior resection, and transabdominal or transvaginal gynecologic surgery including radical hysterectomy, total abdominal hysterectomy, laparoscopic or robotic hysterectomy, vaginal hysterectomy, pelvic organ prolapse repair, bladder surgery and sacrocolpopexy can all potentially result in significant side effects (i.e. urinary retention, urinary incontinence) which appear to involve nerve damage (due to secondary inflammatory effects)—even where the surgeries are carefully designed to spare nerves.
During radical prostatectomy dissection of the bladder neck, mobilization of the neurovascular bundles (NVBs), and transection of the urethra and external sphincter complex may all cause acute neuromuscular injury that is largely responsible for delayed recovery of urinary continence and sexual function. The primary injury results from the mechanical trauma of dissection, nerve traction, and the use of thermal energy (cautery) which leads to neurapraxia or axonotmesis of pelvic autonomic nerves and muscle/cellular degeneration and/or other damage. A secondary (indirect) wave of damage often ensues due to inflammation. The inflammatory cascade includes tissue swelling (edema), activation of coagulation factors, pro-inflammatory cytokine formation, hypoxia, acidosis, free radical production, and apoptosis. White blood cell (macrophage and neutrophil) infiltration with subsequent release of reactive oxygen species and hydrolytic enzymes further contributes to secondary tissue damage. Both modes of injury (primary and secondary) can contribute to varying degrees to the post-operative functional deficits in urinary (i.e. intrinsic sphincter deficiency and detrusor dysfunction) and sexual (i.e. nerve conduction block) function.
Although various drug-based approaches exist to treat inflammation, none of them appear to simultaneously treat the multiple modes of inflammation that follow pelvic surgery; nor do any of them appear to be suited for local application. There remains a need to reduce collateral tissue damage and side effects of pelvic surgery and to improve the rate of functional recovery following pelvic surgery.